Pressure Pots

[bjack99]

I was wondering you uses pressure pots and what your experience has been with them. Do you recommend using them and if so is there a specific one.

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I have a set up that Jason gaga4toyz helped me with. I got a Harbor Freight paint pot but had to plug the hole for the feed tubing, which wasn't a standard size. Then I got another smaller pot from another source and went through the same thing with the feeder hole. I cast a bunch of female heads I did with vacuum molds and they came out pretty good. Some of them were perfect. I just got some slower setting resin because I was using alumilite and i think it was setting up too fast to pressurize sometimes. You can convert almost any paint pot but the Harbor Freight ones are inexpensive. I did come across a reference to a lid blowing off of one of them though. But it's possible the person didn't have proper pressure valve or didn't fasten the lid properly?

Also, the fittings that came with both of the pots I bought from them were bad/damaged/cheap and I replaced with a regulators and filters. I think I should replace the safety valve too after hearing about the mishap online....

Also I called a machine shop and am going to have them ream and retap the holes for a standard plug just to be safe (for the extra hole).

Pressure can be really dangerous. My grandfather was a professional mechanic and he had a compressor shoot like a torpedo right through the back of our garage. However, it does make bubble free castings ;-)

I like to vacuum the molds because I can do it in the house but I keep the air compressor in the garage, just in case something ever goes wrong..... There can be mishaps with vacuum chambers too but if you use the right materials with chamber, I feel it's pretty safe.

The wall was repaired ;-)

[bjack99]

Thanks Laurie. What kind of compressor are you using? And what kind of resin do you use that is slow curing? I envision the resin already setting by the time I get the top of the pressure pot screwed down.

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Thanks Laurie. What kind of compressor are you using? And what kind of resin do you use that is slow curing? I envision the resin already setting by the time I get the top of the pressure pot screwed down.

You're welcome. I have a campbell Hausfeld 15 amp compressor with a 13 gallon tank... It's probably about 3.5 HP which is what alumilite recommends for their resins...

I used their resins but I bought some smoothon resin with a little longer set time and I found another resin from freeman supplies that has a super long set time (called slow set) which I may try if the smoothon doesn't work... Alumilites resin sets up faster than any I've used....

[gaga4toyz]

The extra hole is probably a straight pipe thread instead of a more standard tapered pipe thread. How much are they charging you to fix it? You could probably order some straight pipe thread plugs from mcmaster carr and not have to rethread. I helped Boss make one too and I think that's what we need to do for his.

Presure pot casting is the only way to go. I get flawless castings every time. I use a slower set smooth on plastic with my pot. I think Harbor Freight has the best pressure pot for the money but the regulators and fittings are junk. I also like to add a filter to keep water from blowing into the pot and your plastic. You have to make your mold with a vacuum chamber if you're going to cast in a presssure pot or your parts will have little plastic zits all over them. Another option is to make your molds and then place them in the pressure pot under 45 psi until the molds cure.

I cast everything at 45 psi. I agree with Laurie's specs on the air compressor as well.

Most important thing is working with air pressure can be very dangerous if you use broken or defective equipment or you try to convert something into a pressure pot that can't handle the pressure. You also don't want to max out the air pressure on the pot or go over the pots rateing.

[bjack99]

Thank you both. Are you both referring to the Smooth Cast 321 or 322?

[boss]

I have been using 321 for my new bodies and I find it's just the right amount of time for me to pour and seal the pot (although a couple times I've been rushing it). I've also used 327 (which is probably closer to 322 in terms of set up time). With 327 you have plenty of time to pour the molds and get the pot sealed. The downside is that is can take 7-8 hours for the parts to hard enough for demolding (vs. 321 which takes a half hour or less most times).

[bjack99]

Thank you boss. I got my body yesterday and it looks great!

[boss]

^^ cool. can't wait to see what you do with it.

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The extra hole is probably a straight pipe thread instead of a more standard tapered pipe thread. How much are they charging you to fix it? You could probably order some straight pipe thread plugs from mcmaster carr and not have to rethread. I helped Boss make one too and I think that's what we need to do for his.

ng.

thanks but it's not a pipe thread....